Work machines, such as earth moving trucks, wheel loaders and the like, often utilize a payload monitor to determine how much material is being moved by the machine. Information from the payload monitor may be used to ensure proper loading of the machine, monitor production rates of a machine and numerous other benefits.
U.S. Pat. No. 4,835,719 assigned to Caterpillar Inc. of Peoria, Ill. describes a method for monitoring payload. A plurality of pressure transducers provide data to a microprocessor. The microprocessor calculates the payload based on data received from the transducers. In performing the calculation the processor assumes that the center of gravity of the payload is positioned a predetermined distance between the front and rear axles of the machine. Typically, large trucks were assumed to distribute seventy five percent of the payload on the rear axle and twenty five percent of the weight on the front axle. Actual distribution of the load is in part dependent on the shape of the body or bucket that the load is being carried in.
The owners of these machines occasionally replace original bodies or buckets with custom bodies that are designed for a specific purpose. Often these custom bodies shift the center of gravity of the payload. A shift of even a percent or two in either direction may affect the accuracy of the calculated payload to a larger degree. Having an inaccurate payload system may cause overloading or under loading of the machine. Overloading of the machine could cause damage to the machine, while under loading reduces productivity.
It is desirable to have a payload monitor that can be adjusted to compensate for changes to the machine.